1. Field of the Invention
The present invention is directed to a folding box gluing machine for the production of folding boxes from blanks in a folding station, in which portions of blanks provided with a glue strip are folded, and a subsequent transfer station, which includes as a conveyor mechanism at least two pairs of conveying straps, each having upper and lower straps, and including a device for achieving the sideways removal of defective boxes arranged on the outside adjacent to one of the pairs of conveying straps.
2. Description of the Related Art
As is known, folding box gluing machines include a transfer station behind the last folding station, in which portions of blanks provided with a glue strip are folded. This station feeds the folded boxes, oriented exactly in all of their portions, having glue seams that have not yet hardened, to a subsequent collecting and pressing mechanism. In the collecting and pressing mechanism, a stream of folded boxes is formed, which is then conveyed between pressing belts and maintained under pressure for a desired amount of time, until the glue seams have hardened.
It is known to provide an extracting device in the transfer station in order to remove boxes detected as being defective before the stream of boxes is formed at the collecting and pressing mechanism. The boxes are still delivered singularly and spaced apart from each other by the transfer station, such that an individual box can be removed from the machine. Defective boxes are boxes that are not sufficiently glued, boxes that contain folding errors, or boxes that are identified as not conforming to the job order.
The transfer station includes conveying elements defined by at least two pairs of conveying straps, each including upper and lower straps. An extracting device is defined by a mechanism that is arranged outside along a lateral pair of straps which engage a portion of the box projecting above the straps on the outside, in order to pull the defective box to one side through the pair of conveying straps.
Known devices for pulling the boxes out include turning plate ejectors, which include a turning plate that is driven at high rotary speed and that extends underneath the projecting portions of the box, and clamping elements that are arranged above the projecting portions of the box. When a box is defective, it is fastened against the turning plate by the clamping elements and pulled out from the machine by the rotation of the turning plate. Such a mechanism is described in DE 102 24 814 A1. Turning plate ejectors are secure in operation and require little structural expense. However, turning plate ejectors are only suitable for small to medium size boxes.
Larger boxes are extracted by so-called linear ejectors, as are described in DE 195 02 676 A1. Linear ejectors include two belt conveyors, between which the boxes are clamped and removed from the machine along a linear path. Linear ejectors are very expensive.
Extraction devices that pull the boxes out only on one side have the disadvantage that certain types of boxes do not lend themselves to being extracted. Thus, oversized boxes and boxes having uncovered lengthwise flaps folded inward on both sides cannot be extracted. If such boxes are pulled out to one side, the danger exists that the box will rip a conveying strap from its guide. The reason for this is that the inwardly folded, uncovered lengthwise flap on the far side will open as soon as it is pulled out between the first pair of conveying straps and hit the second pair of conveying straps in the opened state, catching the upper strap. Such nonextractable folding boxes include, for example, four-point boxes.
In order to be able to extract such boxes and oversized boxes, it is known from DE 199 48 017 A1 how to arrange a knife cutter in the conveying direction at the beginning of the transfer station and an extraction device at each lengthwise side of the transfer station. The knife cuts through the boxes in the middle prior to the extraction point, such that one half of the box can be pulled out on either side without difficulty. This type of extraction device is also very expensive. In addition to the lengthwise knife, this extraction device also requires an ejector on each lengthwise side of the transfer station.
Therefore, the problem underlying the present invention is to configure a folding box gluing machine such that even boxes with uncovered lengthwise flaps folded inward on both sides, especially four-point boxes, can be extracted as a single piece to one side.